Liquid electro-photographic (LEP) printing uses a special kind of ink to form images on paper and other print substrates. LEP ink usually includes charged polymer particles dispersed in a carrier liquid. The polymer particles are sometimes referred to as toner particles and, accordingly, LEP ink is sometimes called liquid toner. LEP ink may also include a charge control agent, sometimes called a “charge director”, to help control the magnitude and polarity of charge on the particles. An LEP printing process involves placing an electrostatic pattern of the desired printed image on a photoconductor and developing the image by applying a thin layer of LEP ink to the charged photoconductor. Charged toner particles in the ink adhere to the pattern of the desired image on the photoconductor. The ink image is transferred from the photoconductor to a print substrate, for example through a heated intermediate transfer member, evaporating much of the carrier liquid to dry the ink film, and then to the print substrate as it passes through a nip between the intermediate transfer member and a pressure roller.
Gear teeth are omitted in the figures to more simply illustrate the gear trains. The same part numbers designate the same or similar parts throughout the figures. The figures are not necessarily to scale.